Nowadays, a large number of bulletin board websites exist on the Web, and many discussions are held in a form called “threads” in each site. Among these threads, the notable threads developed into an extensive discussion that has an influence upon even the business activities. However, these notable threads are buried in a huge number of unnoticeable threads. For this reason, a technology to extract the notable thread in conformity with an interest of a user is desired.
As one of such technologies, there is disclosed in JP-A-2003-242176 (which is also published as US 2003/0140309 A1) a method of correcting a weight of a word contained in a topic in which a user is interested, by correcting a weight of a word contained in an E-mail having higher frequency of sending.
However, the technology described in JP-A-2003-242176 cannot correct a weight of the word contained in the topic in which the user is not interested. Also, a weight of the word cannot always be adequately corrected since a wide variety of words are described in the E-mail. As a result, such a problem existed that the topic adapted to the user's interest cannot be extracted adequately.